The N-glycosidic saccharide chains of S-glycoproteins associated with self-incompatibility in Brassica campestris were converted to the pyridylamino derivatives, and their structures were determined with physicochemical data and with the exoglycosidase treatment. These proved to be related to a saccharide chain of pineapple stem bromelain. The three S-glycoproteins, S_8, S_9 and S_<1 2>, carried the common oligosaccharides A and B. This indicates that the specificity of S-glycoproteins was not present in the saccharide chains themselves, but probably in the amino acid sequences.